Unification of Wales

The Unification of Wales was a period of Welsh history from 633 to 949 AD when the Welsh principalities were unified under the leadership of Hywel Dda, King of Deheubarth, after centuries of efforts by Gwynedd to conquer the other Welsh states. By Hywel Dda's death in 949, all of Wales except for Morgannwg and Gwent in the southeast were unified under Deheubarth. However, this unity was short-lived, and Deheubarth's might crumbled following Hywel's death.

Background
In the centuries following the Anglo-Saxon invasions of England, new kingdoms emerged in Wales and Scotland. Early Welsh kingdoms had their origins in the tribal groups of Roman and pre-Roman times such as Dyfed, which derived from the Demetae.

History
Historical developments in Wales in the 6th century are rather obscure. Gildas, in his De Excidio, inveighs against the evils perpetrated by the "Five Tyrants", including Maelgwyn of Gwynedd who died in the late 540s and Vortepor, ruler of the Demetae (or Dyfed). Also around the late 6th century, the kingdom of Powys emerged in central Wales. It was principally these three kingdoms that struggled for supremacy over the next three centuries.

A brief hope of reuniting the Welsh lands with the Britons of the south-west and Cumbria, from whom they had been cut off by the advancing Anglo-Saxons, occurred in the reign of Cadwallon ap Cadfan of Gwynedd. Cadwallon defeated and killed Edwin of Northumbria in the Battle of Hatfield Chase in 633. The triumph was short-lived, however, for in 635 Cadwallon perished in battle against Edwin's brother Oswald at Heavenfield near Hexham.

It was two centuries before another ruler of note took power. Merfyn Frych became King of Gwynedd in 825. During his 19-year reign, he consolidated the kingdom and passed on a strong position to his son, Rhodri Mawr, or Rhodri the Great.

Rhodri expands Gwynedd
It was a moment of opportunity for Gwynedd as the kings of Mercia, who had long harried the principality, were under extreme and fatal pressure from Wessex to the south and Viking invaders. Rhodri, too, had to face the Viking threat, and in 856 he defeated them in a great battle on Anglesey. He also succeeded in expanding his power to the south. Cyngen ap Cadell of Powys died in exile in Rome in 856, probably having been driven out by Rhodri, and the last known independent ruler of Ceredigion, Gwgon, drowned in 872, after which it was annexed by Gwynedd. Rhodri died in 878 and power was divided amongst his six sons. The most active of them, Anarawd ap Rhodri, struggled to contain the twin threats of Alfred the Great's Wessex and resurgent Viking groups who established themselves in Anglesey in 903.

Welsh unity under Hywel
It was Anarawd's nephew Hywel Dda, or Hywel the Good, who achieved the next near-unification off Wales. He became ruler of Dyfed in 910 and strengthened his claim by his marriage to Elen, niece of Rhodri ap Hyfaidd, the last king of the native Dyfed dynasty. By 920, he united Dyfed with the smaller territory of Seisyllwg to create a new kingdom of Deheubarth.

Although he submitted in 927 to Aethelstan of Wessex, it may have been a means of gaining advantage against his great rival Idwal Foel of Gwynedd, who adopted a more openly aggressive anti-English policy. Hywel maintained a more diplomatic stance, vistiing the English court several times and even making a pilgrimage to Rome in 929.

In 942, Idwal launched an attack against England in which he died, and Hywel took advantage to invade Gwynedd before Idwal's sons could claim the throne. This helped him become the king of most of Wales, save Morgannwg and Gwent in the southeast. The rest of his reign was peaceful. On his death in 949, it looked as if the prospects for Welsh unity were bright.

Aftermath
After Hywel Dda's death, Wales became unstable and suffered Viking raids - St. David's monastery was sacked in 999. Gruffydd ap Llywelyn restored the power of Gwynedd from 1023, defeating an English army at Welshpool in 1039 and annexing Deheubarth. However, under pressure from Harold II of England, his support fell away, and he was murdered in 1063. Wales was annexed by Edward I in 1283.